Conventionally, a terminal attachment structure in which a terminal is swaged and fixed to a terminal attachment plate made of metal has been widely used in storage secondary batteries and the like included in industrial electric equipment, automobiles, and the like (Patent Literature 1). Such secondary batteries are configured to include a battery pack having a storage function and one or more pairs of electrode terminals which are attached to a front surface of the battery pack and used for connection with external equipment. In conventional automobiles, a pair of electrode terminals is arranged on a lead-acid battery serving as a battery. Recent hybrid vehicles and electric vehicles include a plurality of lithium ion batteries mounted as secondary batteries. A plurality of electrode terminals have therefore been needed according to the number of lithium ion batteries mounted.
Because of high storage capacity and in view of ensuring stability and safety, such car-mounted secondary batteries use electrode terminals that are formed by working a highly-conductive metal material into a constant thickness and diameter. To obtain favorable conductivity as well as endure vibrations and external impact, the terminals are firmly attached by swaging that is capable of fixing without using an adhesive or the like (Patent Literature 2).
A terminal assembly having the foregoing structure typically includes a terminal attachment plate that can be attached to the surface of a battery pack or the like, and a terminal to be inserted and fixed to the terminal attachment plate. The terminal attachment plate is formed as a thin plate of a metal material, and has a through hole for the terminal to be inserted through. The terminal often includes a terminal main body formed as a circular or prismatic column of a metal material, a flange integrally formed to extend outward from the outer periphery of the terminal main body, and a leg part extending below the flange.
After the leg part extending below the flange is passed through the through hole and the flange is placed on the terminal attachment plate, the terminal is attached by swaging and fixing, i.e., flattening the leg portion against the back side of the terminal attachment plate by using a striking tool such as a punch.